What causes the dry point of gasoline in the fractional distillation column of diesel hydrofining to increase suddenly?
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Our diesel hydrogenation unit combines a fractionating tower with a stabilizing tower. Over the past week, the dry point of gasoline has suddenly increased; therefore, we have tried to control the temperature by increasing the reflux rate. However, this leads to a decrease in the flash point, so we use a reboiler to heat the mixture in order to maintain the appropriate flash point. As a result, the fractionating tower becomes extremely unstable, the tower pressure rises, and there is interference between the flash point and the dry point. It is now very difficult to ensure that the product quality meets the required standards. What actions should be taken to guarantee product quality?
Lowering the tower’s temperature and then increasing the stripping steam will resolve the issue
Check if the boiling ranges of your products overlap
Check the heat exchange process to determine if there are any internal leaks in the equipment
It is possible that the composition of the raw materials has changed, with less gasoline component present; therefore, the distillation volume should be reduced appropriately to control the dry point
Firstly, the main reason for the excessively high dry point of the product at the top of the tower is the vaporization of heavier components; lowering the temperature at the bottom of the tower should help to resolve this issue； Secondly, there are two reasons for the low flash point of the overhead product: one is that excessive reaction occurs earlier on, resulting in lighter components in the feed; the other is that the pressure at the top of the tower is too high, preventing the light components from being removed properly ； At this point, depending on the circumstances, if it is possible to ensure that the product quality is satisfactory, the reaction conditions can be relaxed to reduce excessive reaction ； Or by appropriately reducing the tower pressure to allow the excess light components to go with the acidic gas, it should also be possible to bring things back to normal ；
Yes, our leader reduces the pressure in the reboiler by directing the reflux from the top of the tower, thereby achieving the distillation of light and heavy components
We are responsible for the operation of distillation columns and stabilizer columns; we do not have stripping columns